At least 31 Palestinians have been killed and 170 others injured during an aid distribution in southern Gaza in an incident that's now being called the deadliest of its kind since the war began.
It happened near a newly established aid hub in Rafah, set up by the Israel and US-backed Gaza Humanitarian Foundation.
But what exactly caused the bloodshed remains deeply contested.
Witnesses claim Israeli forces opened fire on a crowd about a kilometre from an aid site in Rafah run by the Gaza Humanitarian Foundation, a private group which uses armed American security contractors.
Sharif Dahalan was there, and says shots were fired from an aircraft.
"They told us to come and collect aid from the crossing. The Americans deliver aid, and we didn't have flour or anything else. We went to get some flour or anything to eat. We were surprised, and before we reached the Muawiyah Mosque, the plane began firing at people."
But the Israeli military tells a different story.
They say their troops did NOT open fire on civilians and offer video evidence suggesting masked men were firing into the crowd.
Another video shows hundreds of people on the ground trying to avoid being hit by gunfire.
Dozens of rounds can be heard being fired, but it is not clear by whom.
Speaking from Rafah, IDF spokesperson Brigadier General Effie Defrin accuses Hamas of sabotage.
"I'm here in the city of Rafah, right behind me you can see one of the distribution centres we opened in the last few days. So far, we opened four distribution centres, and we are intending to open more of them. ... Hamas is doing his best, his utmost to stop us from doing so. He's spreading rumours, fake news, he's trying bluntly and violently to stop the people of Gaza from reaching those distribution centres. ... I urge you not to believe every rumour spread by Hamas. We will investigate each and (every) one of those incidents and each and one of those allegations.”
The International Committee of the Red Cross says 21 people were declared dead on arrival at its field hospital in what it calls a mass casualty influx of civilians with gunshot and shrapnel wounds.
Dr Goher Rahbour is a UK consultant surgeon volunteering at Nasser Hospital.
"I’ve been here for a week as part of a month in Gaza, at Nasser Hospital. Today has to be the worst day in these last seven days which I have experienced. This morning, the day started at 7:45 am when a mass casualty alert went off and we rushed to theatre. We've already completed two laparotomies and it's just after midday at the moment."
Specialist surgeon Khaled al-Ser says most of the injuries were to the upper body.
"The type of injuries range from gunshot wounds, which are the most common, to shrapnel from rocket fire. Most of the gunfire hit the upper torso, abdomen, and chest. To date, we have recorded more than 30 emergency operations, including vascular and surgical procedures, and across various departments."
He added that many of the injured were young men in civilian clothing.
Others were women and children.
All had been there to receive aid.
Meanwhile, the Gaza Humanitarian Foundation says nothing happened at all.
It released security footage showing what it says is a peaceful distribution, with civilians calmly collecting aid.
It called the reports of chaos and mass casualties false.
Still, questions remain.
Independent observers have no access to the sites, which are inside Israeli military zones.
While the Foundation says no shots were fired by its security teams, Israel admits its forces fired warning shots at people approaching from about a kilometre away.
The United Nations and other international aid groups have refused to work with the new distribution system, warning it militarises aid and endangers lives.
Before Sunday, 17 people were killed while trying to reach the hubs, according to the head of the Gaza Strip's Health Ministry’s records department.
Jonathan Whittall, head of the UN humanitarian office in Gaza, says the Foundation's distribution system is not just flawed, it is strategic.
“This newly developed distribution scheme, for lack of a better phrase, is more than just the control of aid. It's essentially engineered scarcity. There'll be four distribution hubs, as we understand it, located in central and southern Gaza, secured by private US security contractors, where those Palestinians that can reach them will receive minimum rations.”
Back at Nasser Hospital, the emergency hasn’t ended.
Doctors are still operating, patients are still arriving, and blood supplies are running low.
Dr Marwan al-Hams, from the Gaza Health Ministry, says even those willing to donate blood are too weak to give.
"We are suffering greatly from a blood shortage. We frequently appeal to people to donate blood, but when the donors arrive, we find that most of these young men are suffering from anaemia due to the starvation war waged by the Israeli occupation against our Palestinian people, and the malnutrition and immunodeficiency that most age groups in the Gaza Strip suffer from."
As Israel pushes to expand the Gaza Humanitarian Foundation system, this incident has fuelled even more mistrust, and fear.
For many in Gaza, the road to humanitarian aid has become a battlefield of its own.
